Grapefruit is a good source of vitamin C,[8][16] pectin fiber,[17] and the pink and red hues contain the beneficial antioxidant lycopene.[8][18] Studies have shown grapefruit helps lower cholesterol[8][19] and there is evidence that the seeds have low levels of antioxidant properties.[20] Grapefruit forms a core part of the grapefruit diet, the theory being that the fruit is low glycemic index is